Right,

So, maybe I was wrong in assuming GCC would mimic ARMCC's behaviour...

On 18 February 2014 15:35, Bernard Ogden <[email protected]> wrote:
> What I'm concerned about is that, at least for armcc, -mfpu=<fp arch> means 
> hard float PCS. So the new behaviour looks like the armcc behaviour, but is 
> different w.r.t. calling convention.

True. In LLVM, -mfpu doesn't change the calling convention.


> In GNU-land, it looks like the only valid parameter of this form is 
> softvfp+vfp, and that only gas accepts this parameter.

Which makes no sense, since "vfp" can be anything. Do I default to the
version compatible with the CPU? Can I set NEON on v7? I don't think
so.


> So although its nice to generalise this to something similar to the armcc 
> behaviour, perhaps the right thing to do here is to support the GNU behaviour 
> only (i.e. just support softvfp+vfp, which seems not to be legal in armcc). 
> Updating the kernel makefiles would be even better, if that's a reasonable 
> thing to do (I don't know why the assembler needs to care about PCS, but I 
> expect that's ignorance).

Maybe using -mfloat-abi=softfp would be the best thing, since it's
supported by both compilers. I'll try to convince them... ;)

cheers,
--renato

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